I have been working on long RT rises and Tartine folding method and something unusual happened this weekend.

Saturday I made two identical batches of dough with one exception:

.02% IDY vs. 2% Italian starter - so hydration on Italian was a little more than the IDY batch (IDY batch was 70% hydration so I assume Italian batch was closer to 71%)

Things went great, doubled in 24 hours, balled for six hours at RT. The IDY balls smelled like dough and the Italian starter smelled like alcohol. I was excited when I fired up the WFO.

Long story short the IDY batch was great. Easily in one of the top batches I have made.

When I went to spread out the Italian culture batch they tore a part very easily. I had 270 gram balls and to keep them from ripping I had to keep them to about 8" pies. They also where very sour. Overfermented?

Two identical batches with the one exception mentioned above. Both batches worked the same way on the same day. I know there has got to be an easy explanation. Can anyone explain it to me?

Yes, it sounds like your starter dough was overfermented. 30 hours at room temp could easily do that. You might try lowering the starter percentage by half and keeping it in a less humid area of the house.